Sheet metal nail and apparatus for testing

ABSTRACT

A hollow sheet metal nail apparatus and apparatus for testing the holding capacity of the nail in which the nail apparatus includes a head connected to a shank constructed of a pair of legs joined to the head by a flexible connection in such a manner that the legs are free to move apart along their lengths. The head of the nail includes a frangible portion which is adapted to rupture when a predetermined force is applied thereto. The apparatus for testing the nail includes an elongated shank with a hook portion at one end to engage the frangible portion of the nail and arranged to facilitate the application of an axial force on the testing apparatus so that the nail can be tested without destroying such nail.

atent 1 nited States Hallock, Jr.

[ SHEET METAL NAIL AND APPARATUS FOR TESTING [22] Filed: Jan. 29, 1973 [21] Appl. N0.: 327,254

[52] US. Cl 116/114 R, 85/11, 85/31 [51] Int. Cl. G0ld 21/00 [58] Field of Search 85/11, 13, 31, 49; 116/114 R [56] References Cited UNITED STATES PATENTS 2,035,389 3/1936 Knutson 85/11 2,745,308 5/1956 Gisondi 1 85/13 2,887,004 5/1959 Stewartm. 85/49 3,466,967 9/1969 Hallock.... 85/11 3,710,672 l/l973 Hallock 85/11 May 28, 1974 Primary Examiner-Louis J. Capozi Attorney, Agent, or FirmA. Yates Dowel], Jr.

[57] ABSTRACT A hollow sheet metal nail apparatus and apparatus for testing the holding capacity of the nail in which the nail apparatus includes a head connected to a shank constructed of a pair of legs joined to the head by a flexible connection in such a manner that the legs are free to move apart along their lengths. The head of the nail includes a frangible portion which is adapted to rupture when a predetermined force is applied thereto. The apparatus for testing the nail includes an elongated shank with a hook portion at one end to engage the frangible portion of the nail and arranged to facilitate the application of an axial force on the testing apparatus so that the nail can be tested without destroying such nail.

4 Claims, 6 Drawing Figures BACKGROUND OF THE INVENTION 1 Field of the Invention This invention relates generally to fasteners of various kinds and relates particularly to sheet metal nails for attaching covering material to lightweight building material, as well as to apparatus for testing the holding capacity of the nail.

2. Description of the Prior Art Historically, nails and other fasteners have been provided for attaching covering materials to a plurality of building materials to enhance the appearance of a structure as well as to protect the structure from the elements. Initially the building material most commonly used was wood and a conventional nail or screw was satisfactory for attaching covering material to such structure. As buildings grew in size, bricks and concrete, either reinforced or not, were utilized for strength and permanency and special fasteners were provided for attaching covering material to concrete structures either before or after such structures had reached their maximum strengths. Due to the weight problem, the industry has continued to experiment in an effort to produce lightweight, high-strength building materials having insulating and fire resistant qualities.

It has been found that vermiculite, pearlite, and the like materials can be mixed with cement in varying proportions to produce a desired building material which is light in weight, as compared to concrete, and which displays high strength, insulating, and fire resistance characteristics. Such a building material currently is being manufactured by W. R. Grace and Co., Construction Products Division, Cambridge, Massachusetts, under the trade name Zonolite. During the initial drying period of the lightweight aggregate material, it is desirable to attach a protective covering to the aggregate to protect such material, as well as to provide a base upon which finish materials can be applied. Some effort has been made to provide a fastener for attaching a base ply covering material to lightweight building material such as the structure of the patent to Robert L. Hallock, U.S. Pat. No. 3,710,672. This structure has been satisfactory for holding the base ply to the building material; however, such material has presented special problems since the building material must attain a compressive strength not less than approximately PSUZQfP hqfas snesa 952.129. earlie t.

Also. the mixture of materials has been critical and, therefore, it has been necessary to test the strength of the building material.

The strength of the material can be tested by a conventional penetrometer, however, such an instrument normally is not available at ajob site. It has been found that the material sets up rapidly and can be walked on soon after pouring and that the fasteners can be used for testing the compressive strength of the material. Normally the material is tested by driving one or more fasteners into the material and then pulling one or more fasteners therefrom. If the fasteners can be extracted easily, the building material has not reached sufficient compressive strength and, therefore, such material is permitted to harden further. If fasteners cannot be extracted easily and remove a plug of building material, then the material has reached sufficient compressive 2 strength. The removal of a fastener with a plug destroys the fastener andleaves a hole in the building material and the base ply.

SUMMARY OF THE INVENTION The present invention is a sheet metal nail for attaching covering material or a base ply to a lightweight building material containing a mixture of vermiculite, pearlite or the like combined with cement in which the fastener is provided with a frangible element adapted to rupture when a predetermined force is applied without destroying the fastener, as well as a tool used in applying the force necessary to rupture the frangible element.

The fastener includes a sheet metal head having a pair of legs arranged in a manner such that portions of the legs spread apart when the fastener is driven and such head includes a frangible portion or element located in a position accessible to a hook portion of a tool so that when the tool is applied to the fastener and a predetermined force is exerted on the tool, the frangible portion of the fastener ruptures without destroying the usefulness of the fastener.

It is an object of the invention to provide a sheet metal fastener having a frangible element accessible for a testing tool and such frangible element is adapted to break when a predetermined force is applied thereto by the tool.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective illustrating one application of the invention.

FIG. 2 is a side elevation of the fastener and the tool.

FIG. 3 is a perspective illustrating the fastener before application to the building material.

FIG. 4 is a section on the line 44 of FIG. 3.

FIG. 5 is a fragmentary perspective of a fastener applied to building material and with the testing appara tus in position to test the fastener.

FIG. 6 is a perspective similar to FIG. 5 of a fastener which has been tested and the frangible element has ruptured.

DESCRIPTION OF THE PREFERRED EMBODIMENT With continued reference to the drawing, a nail or fastener 10 is provided having a head 11 connected to one end of an elongated hollow shank l2 and the opposite end of such shank has a penetrating portion 13. The shank includes a pair of opposed generally U- shaped legs 14 in facing relationship with each other to define a hollow tubular member when the legs are closed. Each of the legs includes a pair of generally parallel sides 14 connected by a web or back 16. The back 16 of each of the legs is curved or bowed inwardly intermediate the ends, while the upper and lower ends of the legs are of substantially similar configuration.

Each of the backs 16 is connected by a hinge portion 17 to the bottom surface of the head 11 so that when the nail is driven into relatively rigid material, such as lightweight aggregate l8 constructed of expanded vermiculite, pearlite, or the like mixed with cement, the curvature of the backs 16 causes the legs 14 to spread apart, as illustrated in FIGS. 2, 5 and 6. The nails are driven into the lightweight aggregate when the aggregate has partially set up and before the aggregate has 3. attained a substantial degree of hardness and such nails are usedto fasten a protective covering material or base ply 19 to the aggregate.

in penetrating the aggretage, most of the inner and outer surfaces of the legs 14 intimately engage such aggregate so that the aggregate is bonded to the legs when the aggregate is set and hardened. When the legs 14 spread apart, such legs capture a plug of material 20 between the legs so that the frictional engagement between the legs and the aggregate on the interior and exterior thereof is stronger than the bond between the plug 20 and the surrounding material of the aggregate.

The head 11 is constructed of sheet metal having a desired tensile strength and such head is provided with a central aperture 22 having a thin strip or bridge 23 extending across the same. The opposite ends of the bridge normally are integrally connected to the head 11 with portions of the aperture 22 disposed on opposite sides of the bridge. It is contemplated that a separate strip of material having a known tensile strength could be disposed across the aperture with opposite ends welded or otherwise attached to the head 11. Care should be taken to make certain that the connection between the ends of the strip and the head is stronger than the tensile strength of the strip so that the strip will break before either end comes loose from the head.

in order to test the holding capacity of the nail 10, a tool 24 is provided having an elongated shank 25 with a hook 26 at one end and a ring 27 at the opposite end. The ring 27 is adapted to receive a handle, such as the handle of a hammer 28 (FIG. 1), dowel rod, strip of wood, or the like. The handle is gripped by a workman who applies an upward force to the tool 24 after the hook 26 has been inserted into the aperture 22 to underlie the bridge 23. It is apparent that if desired the shank 25 of the tool could be directy and permanently attached to a handle.

In the use of the apparatus, after the aggregate 18 has been poured and has taken an initial set, the covering material or base ply 19 is placed on the upper surface of the aggregate after which a plurality of fasteners are driven through the covering material into the aggregate. lt is recommended that fasteners be applied at least every nine inches along the laps of the covering material and be arranged in a pattern of 18 inches on centers in the field or expanse of the covering material.

Before the finish material can be applied to the covering material, the holding capacity of the fastener must be tested and in order to do this, the hook 26 of the tool 24 is inserted through the aperture 22 in the fastener head so that the hook underlies the bridge 23 after which an upward force is applied to the tool; If the aggregate releases the legs 14 of the fastener, such fastener will be retracted in a reverse manner from when the fastener was driven and this indicates that the holding capacity of the fastener is not strong enough. lf the aggregate fails to release the legs 14 when an upward force is applied to the tool 24, such upward force causes the bridge 23 to rupture, as illustrated in FIG. 6, without destroying the fastener which indicates that the aggregate has reached sufficient compressive strength to support the finish material and therefore such finish material can be applied. Preferably several fasteners in each section of the aggregate should be tested before the finish material is applied.

I claim:

I. A sheet metal nail for attaching a covering material to a lightweight aggregate building material, said nail comprising a head, an elongated shank connected at one end to said head and having a penetrating portion at the end remote from said head, said shank including at least two legs, a portion of each leg being hingedly connected to said head and the remaining portion of each leg being free to move relative to said head, said head having an opening extending axially therethrough, a frangible member carried by said head and extending across said opening, the opposite ends of said frangible member being connected to said head, said frangible member being of a width less than the width of said opening, whereby said frangible member is adapted to rupture when a predetermined force is applied thereto.

2. A sheet metal nail comprising a head, an elongated shank connected at one end to said head and having a penetrating portion at the opposite end, a frangible member carried by said head in a position to permit the nail to be driven, said frangible member having a tensile strength which ruptures when a predetermined force is applied thereto, whereby when the nail is driven, a predetermined withdrawal force applied to said frangible member causes said frangible member to rupture when the holding capacity of the nail is greater than the tensile strength of the frangible member.

3. The structure of claim 2 in which said head has an opening extending therethrough along an axis substantially parallel to the axis of said shank, and said frangible member extends across said opening.

4. The structure of claim 2 in which said frangible member is an integral part of said head. 

1. A sheet metal nail for attaching a covering material to a lightweight aggregate building material, said nail comprising a head, an elongated shank connected at one end to said head and having a penetrating portion at the end remote from said head, said shank including at least two legs, a portion of each leg being hingedly connected to said head and the remaining portion of each leg being free to move relative to said head, said head having an opening extending axially therethrough, a frangible member carried by said head and extending across said opening, the opposite ends of said frangible member being connected to said head, said frangible member being of a width less than the width of said opening, whereby said frangible member is adapted to rupture when a predetermined force is applied thereto.
 2. A sheet metal nail comprising a head, an elongated shank connected at one end to said head and having a penetrating portion at the opposite end, a frangible member carried by said head in a position to permit the nail to be driven, said frangible member having a tensile strength which ruptures when a predetermined force is applied thereto, whereby when the nail is driven, a predetermined withdrawal force applied to said frangible member causes said frangible member to rupture when the holding capacity of the nail is greater than the tensile strength of the frangible member.
 3. The structure of claim 2 in which said head has an opening extending therethrough along an axis substantially parallel to the axis of said shank, and said frangible member extends across said opening.
 4. The structure of claim 2 in which said frangible member is an integral part of said head. 